CN102907060A - Retuning gaps and scheduling gaps in discontinuous reception - Google Patents

Abstract

A method for scheduling, by a wireless transmit/receive unit, when a retune gap occurs, the method comprising detecting a retune trigger event; if the trigger event is detected, determining a time period when the retune gap occurs; and Perform radio frequency front-end retuning during retuning gaps.

Description

Retuning gaps and scheduling gaps in discontinuous reception

Cross References to Related Applications

This application claims priority to U.S. Provisional Application 61/347,997, filed May 25, 2010, U.S. Provisional Application 61/348,510, filed May 26, 2010, and U.S. Provisional Application 61/356,359, filed June 18, 2010 , the content of which application is hereby incorporated by reference.

Background technique

The Discontinuous Reception (DRX) procedure in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Release 8 and Release 9 determines the periodicity of Physical Downlink Control Channel (PDCCH) reception. PDCCH reception and configured semi-persistent scheduling determines the Physical Downlink Shared Channel (PDSCH) on the Downlink (DL) Component Carrier (CC) and the Physical Uplink Shared Channel (PUSCH) on the Uplink (UL) CC When the transmission will occur.

In LTE Release 8/9 (also applicable to LTE Release 10), the network may configure parameters for discontinuous reception (DRX) for the WTRU. The function of DRX is to allow the WTRU not to monitor or decode the PDCCH in order to reduce the energy consumption of the WTRU. The DRX functionality relies on a specific set of rules based on the PDCCH activity of many specific RNTIs. These rules ensure that the network and the WTRU are properly synchronized as to when control signaling can be used to reach the WTRU.

LTE-Advanced (LTE Release 10) is an evolution aimed at increasing the data rate of LTE Release 8/9 using bandwidth extension, also known as Carrier Aggregation (CA), among other methods. Using CA, a WTRU may simultaneously transmit and receive on the PUSCH and PDSCH (respectively) of multiple component carriers (CCs). Up to five CCs can be used in UL and DL, thus supporting flexible bandwidth allocation up to 100MHz.

Contents of the invention

A method for scheduling when a retuning (retun) gap occurs for a wireless transmit/receive unit, comprising: detecting a retuning trigger event; in case the triggering event is detected, determining a time period when the retuning gap occurs; And performing radio frequency front-end retuning during the retuning gap.

Description of drawings

Examples are given in conjunction with the accompanying drawings, and the present invention will be understood in more detail from the following description, wherein:

FIG. 1A is a system block diagram of an exemplary communication system in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system block diagram of an exemplary wireless transmit/receive unit (WTRU) for the communication system shown in FIG. 1A;

FIG. 1C is a system block diagram of an exemplary radio access network and an exemplary core network for the communication system shown in FIG. 1A;

Figures 2A-2B illustrate several exemplary carrier aggregation deployment scenarios;

Figure 3 is a timing diagram illustrating an exemplary DRX cycle;

4A-4C are flowcharts of a method for determining a WTRU-based retuning gap;

FIG. 5 is a timing diagram of a multi-CC DRX cycle;

Figure 6 is a timing diagram in which the activation period is as long as the DRX cycle; and

Figure 7 is a timing diagram in which the activation period is as long as the DRX on duration (On Duration).

Detailed ways

FIG. 1A is a system block diagram of an example communication system 100 in which one or more disclosed embodiments may be implemented. Communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 can enable multiple wireless users to access these contents through the sharing of system resources (including wireless bandwidth). For example, communication system 100 may use one or more channel access methods such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA) and more.

As shown in FIG. 1A, a communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, although it is understood that the disclosed embodiments may encompass any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in wireless communications. As examples, WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, cellular telephones, personal digital assistants ( PDA), smart phones, laptop computers, netbooks, personal computers, wireless sensors, consumer electronics, etc.

The communication system 100 may also include a base station 114a and a base station 114b, each of the base stations 114a, 114b may be configured to wirelessly interact with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more Any type of device for a communication network (eg, core network 106, Internet 110, and/or network 112). For example, base stations 114a, 114b may be base transceiver stations (BTS), Node Bs, eNodeBs, Home NodeBs, Home eNodeBs, site controllers, access points (APs), wireless routers, and the like. Although each of the base stations 114a, 114b is described as a single element, it is understood that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

Base station 114a may be part of RAN 104, which may also include other base stations and/or network elements such as base station site controllers (BSCs), radio network controllers (RNCs), relay nodes (not shown) . Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic area, which may be referred to as a cell (not shown). A cell may also be divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, one for each sector of the cell. In another embodiment, the base station 114a may use multiple-input multiple-output (MIMO) technology, and thus may use multiple transceivers for each sector of the cell.

Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 may be established using any suitable radio access technology (RAT).

More specifically, as previously mentioned, the communication system 100 may be a multiple access system, and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, base station 114a and WTRUs 102a, 102b, 102c in RAN 104 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish over-the-air Interface 116. WCDMA may include technologies such as High Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High Speed Downlink Packet Access (HSDPA) and/or High Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114a and WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved-UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) to establish the air interface 116 .

In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement protocols such as IEEE 802.16 (ie, Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001x, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Radio technologies such as Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN).

By way of example, base station 114b in FIG. 1A may be a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may use any suitable RAT, for facilitating communication in a network such as a business, home, vehicle, campus, etc. communication links in local areas such as In one embodiment, the base station 114b and WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and WTRUs 102c, 102d may use a cellular based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish picocells and femtocells. As shown in FIG. 1A , base station 114b may have a direct connection to the Internet 110 . Thus, the base station 114 b does not have to access the Internet 110 via the core network 106 .

The RAN 104 may be in communication with a core network 106, which may be configured to provide voice, data, application, and/or Voice over Internet Protocol (VoIP) services to one of the WTRUs 102a, 102b, 102c, 102d or more of any type of network. For example, core network 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet interconnection, video distribution, etc., and/or perform advanced security functions, such as user authentication. Although not shown in FIG. 1A , it should be understood that RAN 104 and/or core network 106 may communicate directly or indirectly with other RANs, and these other RATs may use the same RAT as RAT 104 or a different RAT. For example, in addition to connecting to RAN 104, which may employ E-UTRA radio technology, core network 106 may also communicate with other RANs (not shown) using GSM radio technology.

Core network 106 may also serve as a gateway for WTRUs 102a, 102b, 102c, 102d to access PSTN 108, Internet 110, and/or other networks 112. PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a system of globally interconnected computer networks and devices using common communication protocols such as TCP, User Datagram Protocol (UDP) and IP. Network 112 may include wired or wireless communication networks owned and/or operated by other service providers. For example, network 112 may include another core network connected to one or more RANs, which may use the same RAT as RAN 104 or a different RAT.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d may include devices for communicating with different wireless networks over multiple communication links. multiple transceivers. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a using cellular-based radio technology and with a base station 114b using IEEE 802 radio technology.

1B is a system block diagram of an example WTRU 102. As shown in FIG. 1B , WTRU 102 may include processor 118, transceiver 120, transmit/receive element 122, speaker/microphone 124, keypad 126, display/touchpad 128, non-removable memory 106, removable memory 132 , power supply 134 , global positioning system (GPS) chipset 136 and other peripherals 138 . It should be understood that the WTRU 102 may include any subset combination of the elements described above while remaining consistent with the above embodiments.

Processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller device, application specific integrated circuit (ASIC), field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), state machine, etc. Processor 118 may perform signal encoding, data processing, power control, input/output processing, and/or any other function that enables WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120 , which may be coupled to transmit/receive element 122 . Although processor 118 and transceiver 120 are depicted in FIG. 1B as separate components, it is understood that processor 118 and transceiver 120 may be integrated together into an electronic package or chip.

Transmit/receive element 122 may be configured to transmit signals to or receive signals from a base station (eg, base station 114a ) over air interface 116 . For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive, for example, IR, UV or visible light signals. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF signals and optical signals. It should be understood that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Furthermore, although the transmit/receive element 122 is depicted in FIG. 1B as a single element, the WTRU 102 may include any number of transmit/receive elements 122 . More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (eg, multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

Transceiver 120 may be configured to modulate signals to be transmitted by transmit/receive element 122 and to demodulate signals received by transmit/receive element 122 . As noted above, the WTRU 102 may be multi-mode capable. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via various RATs, such as UTRA and IEEE 802.11.

The processor 118 of the WTRU 102 may be coupled to a speaker/microphone 124, a keyboard 126, and/or a display/touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light emitting diode (OLED) display unit), and may Receive user input data. Processor 118 may also output data to speaker/microphone 124 , keyboard 126 and/or display/touchpad 128 . Additionally, processor 118 may access information from, and store data in, any type of suitable memory, such as non-removable memory 106 and/or removable memory 132 . Non-removable memory 130 may include random access memory (RAM), read only memory (ROM), hard disk, or any other type of memory storage device. Removable memory 132 may include a Subscriber Identity Module (SIM) card, a memory stick, a Secure Digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in memory not physically located on the WTRU 102 but on a server or home computer (not shown).

Processor 118 may receive power from power supply 134 and may be configured to distribute power to and/or control power to other components in WTRU 102. Power source 134 may be any device suitable for powering WTRU 102. For example, the power source 134 may include one or more dry cells (eg, nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (eg, longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and/or based on information received from two or more neighboring base stations The timing of the signal to determine its position. It should be appreciated that the WTRU 102 may obtain location information by any suitable method of location determination while remaining consistent with the embodiments.

模块、调频（FM）无线电单元、数字音乐播放器、媒体播放器、视频游戏机模块、因特网浏览器等等。Processor 118 may also be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality, and/or wired or wireless connectivity. For example, peripherals 138 may include an accelerometer, an electronic compass (e-compass), a satellite transceiver, a digital camera (for photo or video), a Universal Serial Bus (USB) port, a vibrating device, a television transceiver, Hands-free headset, blue

modules, FM radio units, digital music players, media players, video game console modules, Internet browsers, and more.

Figure 1C is a system block diagram of the RAN 104 and the core network 106, according to one embodiment. As noted above, the RAN 104 may communicate with the WTRUs 102a, 102b, and 102c over the air interface 116 using UTRA radio technology. RAN 104 can also communicate with core network 106.

The RAN 104 may contain eNodeBs 140a, 140b, 140c, but it should be understood that the RAN 104 may contain any number of eNodeBs while remaining consistent with the embodiments. Each of the eNodeBs 140a, 140b, 140c may contain one or more transceivers that communicate over the air interface 116 with the WTRUs 102a, 102b, 102c. In one embodiment, eNodeBs 140a, 140b, 140c may implement MIMO technology. Thus, eNode B 140a may, for example, use multiple antennas to transmit wireless signals to and receive wireless signals from WTRU 102a.

Each of the eNodeBs 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling in the uplink and/or downlink user etc. As shown in Figure 1C, the eNodeBs 140a, 140b, 140c can communicate with each other through the X2 interface.

The core network 106 shown in FIG. 1C may include a mobility management gateway (MME) 142 , a serving gateway 144 and a packet data network (PDN) gateway 146 . Although each of the above elements are described as being part of the core network 106, it should be understood that any of these elements may be owned and/or operated by entities other than the core network operator.

The MME 142 may be connected to each of the eNodeBs 142a, 142b, 142c in the RAN 104 through the S1 interface and may act as a control node. For example, the MME 142 may be responsible for authenticating the user of the WTRU 102a, 102b, 102c, bearer activation/deactivation, selection of a specific serving gateway during initial attach of the WTRU 102a, 102b, 102c, etc. MME 142 may also provide control plane functionality for handover between RAN 104 and a RAN (not shown) using other radio technologies such as GSM or WCDMA.

Serving Gateway 144 may be connected to each of eNodeBs 140a, 140b, 140c in RAN 104 through an S1 interface. Serving Gateway 144 may generally route and forward user data packets to and from WTRUs 102a, 102b, 102c. The Serving Gateway 144 may also perform other functions such as anchoring the user plane during eNodeB handover, triggering paging when downlink data is available to the WTRU 102a, 102b, 102c, managing and storing the context of the WTRU 102a, 102b, 102c etc.

Serving Gateway 144 may also be connected to PDN Gateway 146, which may provide WTRU 102a, 102b, 102c access to a packet-switched network, such as the Internet 110, thereby facilitating communication between WTRU 102a, 102b, 102c and IP-enabled devices. communication between.

Core network 106 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network, such as the PSTN 108, thereby facilitating communication between the WTRUs 102a, 102b, 102c and traditional landline communication equipment. For example, core network 106 may include, or may be in communication with, an IP gateway (eg, an IP Multimedia Subsystem (IMS) server) that acts as an interface between core network 106 and PSTN 108. Additionally, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to a network 112, which may include other wired or wireless networks owned and/or operated by other service providers.

Radio resource control (RRC) signaling may configure a wireless transmit/receive unit (WTRU) with discontinuous reception (DRX) functionality that controls the WTRU's PDCCH monitoring activity for: the WTRU's cell radio network temporary identity symbol (C-RNTI), RNTI for sending transmit power control (TPC) commands applicable to the physical uplink control channel (TPC-PUCCH-RNTI), RNTI for sending TPC commands applicable to PUSCH ( TPC-PUSCH-RNTI), and semi-persistent scheduling C-RNTI (if configured).

PDCCH is conceptually divided into two different regions. The set of CCE locations on which the WTRU can discover DCIs to operate on is called a search space (SS). SS is conceptually divided into common SS (CSS) and WTRU specific SS (UESS). The CSS is common to all WTRUs monitoring a given PDCCH, while the UESS is different for each WTRU. The two SSs may overlap for a given WTRU in a given subframe because that is what the randomization function is for, and the overlap is different for every subframe.

Depending on the WTRU's connection to the network, capabilities and supported features, the WTRU monitors one or more of the RNTIs described below for authorization, allocation and other control information from the eNB.

System information RNTI (SI-RNTI) is cell specific to indicate system information scheduling on PDSCH in CSS.

A paging-RNTI (P-RNTI) may be assigned to multiple WTRUs for decoding paging notifications in CSS (mainly in idle mode).

The Random Access RNTI (RA-RNTI) is used to indicate the scheduling of the Random Access Response on the PDSCH and clearly identify which time-frequency resource is used by the WTRU to send the Random Access Preamble.

The Multimedia Broadcast and Multicast Service (MBMS) RNTI (M-RNTI) is cell-specific and is used to decode change notifications on the MBMS Control Channel (MCCH) in the CSS.

The Cell RNTI (hereinafter referred to as C-RNTI) is a WTRU-specific RNTI used to decode PDCCH for contention-free grants and assignments; typically used for DCI in UESS.

The temporary C-RNTI is typically used to decode Message 4 for contention-based procedures, and/or until the WTRU gets its own C-RNTI assigned.

Semi-persistent scheduling C-RNTI (SPS-C-RNTI) is typically used in UESS to activate semi-persistent DL allocation on PDSCH or UL grant on PUSCH.

When the WTRU is in RRC_CONNECTED mode, and if DRX is configured, the WTRU may monitor the PDCCH discontinuously using DRX operation; otherwise, the WTRU monitors the PDCCH continuously. When using DRX operation, the WTRU may also monitor the PDCCH according to other requirements. RRC controls DRX operation by configuring several timers, which include: on-duration timer, drx inactivity timer, drx retransmission timer (except for the broadcast process, each DL hybrid automatic repeat request ( HARQ) process), long DRX cycle, drx start offset timer value, and optional drx short cycle timer and short DRX cycle. A HARQ round trip time (RTT) timer for each DL HARQ process (except the broadcast process) is also defined.

When the DRX cycle is configured, the active time includes the time: the duration timer, drx inactivity timer, drx retransmission timer or mac contention resolution timer is running; the scheduling request is sent on the PUCCH and is suspended pending; a UL grant for pending HARQ retransmissions occurs and there is data in the corresponding HARQ buffer; or after successful reception of a random access response with a preamble not selected by the WTRU, no A PDCCH indicating a new transmission for the WTRU's C-RNTI is received.

During the active time period, for a PDCCH subframe, if the subframe is not necessary for UL transmissions for half-duplex Frequency Division Duplex (FDD) WTRU operation, and if the subframe is not part of a configured measurement gap, the WTRU may Monitor PDCCH. If the monitored PDCCH indicates DL transmission or if a DL allocation has been configured for the current subframe, the WTRU may start the HARQ RTT timer for the corresponding HARQ process and stop the drx retransmission timer for the corresponding HARQ process. If the monitored PDCCH indicates a new transmission (DL or UL), the WTRU may start or restart the drx inactivity timer.

In 3GPP LTE Release 10, a WTRU may connect to one or more UL and/or one or more DL CCs via carrier aggregation. When enabling and/or disabling transmission on any component carrier, the WTRU may re-tune the radio frequency (RF) front end to minimize necessary processing and battery consumption. In general, component carriers can be enabled and disabled depending on traffic needs and radio conditions. This can be done by explicit activation or deactivation signaling, a stand-alone DRX procedure or some combination of both procedures. Explicit activation or deactivation signaling from the enhanced Node B (eNB) to the WTRU may be used, which may include layer 1 (PDCCH) signaling, layer 2 (MAC control element ( CE)) signaling or Layer 3 (RRC) signaling.

Release 8/9 DRX procedures may also be applied in this case. The DRX status may be determined independently for each CC or different subsets of CCs according to existing or similar Release 8/9 procedures. The DRX state of a CC or CC subset is mutually exclusive with other configured CCs. The DRX state is common across all configured CCs such that an event on any one CC affects the DRX state of all CCs. If independent DRX is applied, whenever a CC or a subset of CCs enters or leaves DRX, the same RF front-end retuning used for explicit activation or deactivation can be applied, reducing processing and power requirements.

To allow for reasonable WTRU battery consumption when carrier aggregation (CA) is configured, a DL activation or deactivation mechanism for the secondary cell (SCell) is supported (ie, activation or deactivation does not apply to the primary cell (PCell)). When an SCell is deactivated, the WTRU does not need to receive the corresponding PDCCH or PDSCH, nor does it need to perform CQI measurements. Conversely, when an SCell is active, the WTRU may receive PDSCH and PDCCH (if the WTRU is configured to monitor PDCCH from that SCell) and is expected to be able to perform CQI measurements. But in the UL, the WTRU can transmit on the PUSCH of any SCell when scheduled on the corresponding PDCCH (ie, without explicit activation of the SCell on the UL).

The activation or deactivation mechanism is based on a combination of MAC CE and deactivation timer. The MAC CE carries a bitmap for DL activation and deactivation of the SCell: a bit set to 1 indicates the activation of the corresponding SCell, while a bit set to 0 indicates the deactivation of the corresponding SCell. Using the bitmap, SCells can be activated and deactivated individually, a single activate or deactivate command can activate or deactivate a subset of SCells. One deactivation timer is maintained for each SCell, but RRC configures a common value for each WTRU.

Since variable data rate traffic is supported, transmission and reception on the CC will need to be enabled and disabled frequently for performance optimization as well as considerations to drive WTRU processing minimization and battery life.

Figure 2 illustrates several potential deployment scenarios for CAs. In Release 10, for UL, the emphasis is on supporting intra-band carrier aggregation (eg, case #1, and cases #2 and #3 when F1 and F2 are located in the same frequency band). For DL, Release 10 can support all scenarios shown in FIG. 2 .

In LTE Release 8/9, the network (eg, eNB) uses the PDCCH to allocate PDSCH resources for DL transmissions and grants PUSCH resources for UL transmissions to terminal devices (hereafter referred to as WTRUs). A WTRU may request radio resources for UL transmissions by sending a scheduling request (SR) to the eNB. The SR may be transmitted on a dedicated resource (D-SR) on the PUCCH (if configured) or otherwise using a random access procedure (RA-SR). For transmission on PUSCH, the eNB grants radio resources to the WTRU as indicated in the grant received on the PDCCH in the configured resources (UL grant for semi-persistent scheduling).

In LTE Release 8/9, where the network only assigns a pair of UL and DL carriers to a WTRU is a separate carrier system, for any given subframe there is a single HARQ process active for the UL and a single HARQ process for the DL A single HARQ process active in .

For LTE Release 8/9, the WTRU may receive multiple control information messages (i.e., DCI) on the PDCCH in each subframe according to the following: One UL grant and one DL allocation; and if there is at most one message with P-RNTI (paging) and one message in CSS with SI-RNTI (SI change notification).

The benefits of DRX thus go beyond saving some processing of the PDCCH. For subframes in which the WTRU does not need to monitor the PDCCH for UL grants and DL allocations, the WTRU implementation may choose to switch off at least some of its transceiver circuitry, possibly including memory components and/or some baseband components (if the WTRU does not monitor the subframes for the PDCCH The number is sufficiently large, for example, tens of milliseconds).

Figure 3 shows an exemplary DRX cycle. In LTE Release 8/9, a WTRU typically initiates a random access (RA) procedure when one of the following events occurs. When a WTRU makes initial access to the network to establish an RRC connection. When a WTRU accesses a target cell during a handover procedure. When the WTRU performs an RRC connection re-establishment procedure. When the WTRU is instructed by the network to perform an RA procedure (ie, via a PDCCH RA order, typically for DL data arrival). When a WTRU performs a scheduling request, but does not have dedicated resources on the PUCCH for the request, there is typically new UL data to transmit at the WTRU that has a higher priority than existing data in the WTRU's buffer grade time.

Depending on whether the WTRU is allocated dedicated RACH resources (e.g., specific preamble and/or PRACH resources), the RA procedure may be contention-free (CFRA) or contention-based (CBRA) and include the following steps . First, a preamble is transmitted on the resources of the PRACH. Second, a Random Access Response (RAR) is received that includes a grant for UL transmission and a Timing Advance Command (TAC).

Perform two additional steps for CBRA. The third is the transfer of Layer 2/Layer 3 (ie, the actual RA procedure) messages. Fourth, contention resolution is performed, where the WTRU determines whether the WTRU successfully completed the RACH procedure based on the C-RNTI on the PDCCH or the WTRU contention resolution indicator on the DL-SCH.

In LTE Release 8/9, RRC may be used to configure a WTRU with dedicated resources for transmission of CQI, PMI or RI reports and for scheduling requests (D-SRs). In addition, the WTRU may be configured with dedicated UL resources for SPS, i.e., may be configured with PUSCH resources for UL SPS, and for HARQ acknowledgment (ACK)/negative acknowledgment (NACK) (A/N ) UL PUCCH resources. The network also allocates dedicated SRS resources to the WTRU to assist in scheduling decisions in the UL resources allocated for PUSCH transmissions.

In LTE Release 8/9, before the WTRU performs UL transmissions for periodic SRS, or UL transmissions on PUCCH (i.e., HARQ A/N feedback; SR; periodic CQI, PMI, or RI reporting) or PUSCH , the WTRU needs to have proper time alignment with the network. UL synchronization is initially done using RACH procedures, after which the network sends TACs in the DL to maintain proper time alignment. TAC is received in RAR during RA procedure or in Time Advance MAC CE.

After receiving the TAC, the WTRU restarts the TA timer (TAT). While TAT is running, the WTRU may transmit on PUCCH resources in subframes for which the WTRU does not perform PUSCH transmissions (single carrier property). PUCCH resources are dynamically allocated for HARQ A/N feedback of PDSCH transmission in the frequency or time shared resources of the PUCCH region. The WTRU determines which PUCCH resource to use based on the first CCE of the DCI received on the PDCCH, which CCE indicates the PDSCH allocation.

TAT may terminate for a synchronized WTRU when the WTRU does not receive a TAC from the network for a period at least equal to the TAT configuration value (ie, Time Alignment Timer, which ranges from 500ms to 10240ms, if enabled). In case all TACs are lost during the period, ie, after consecutive losses of multiple TACs, the WTRU may not receive a TAC, which is a rare error condition that can be minimized by the scheduler enforcement with sufficient repetition. Alternatively, to implicitly release dedicated UL resources when the network no longer schedules the WTRU for new transmissions, the WTRU may not receive a TAC if the network does not send any TAC. The validity of the WTRU timing advance is entirely under the control of the eNB.

Upon TAT termination, the WTRU releases its dedicated UL resources, including any configured SRS resources, and PUCCH resources for D-SR, CQI/PMI/RI; and any configured DL and UL SPS resources.

Furthermore, once the WTRU is deemed not to be synchronized with the network, the WTRU may not perform any PUCCH or PUSCH synchronization. One reason for avoiding UL transmissions from out-of-sync WTRUs is to avoid possible interference with other WTRUs' transmissions. Additionally, avoiding UL transmissions provides an implicit means for the scheduler to withdraw dedicated UL resources simply by having the TAT terminate after lack of TAC from the network.

Control information for scheduling PDSCH and PUSCH may be sent on one or more PDCCHs. In addition to LTE Release 8/9 scheduling using one PDCCH for a pair of UL and DL carriers, cross-carrier scheduling is also supported for a given PDCCH, allowing the network to provide PDSCH allocation and /or PUSCH authorization.

For an LTE Release 10 WTRU operating with CA, there is one HARQ entity per CC, and each HARQ entity has eight HARQ processes, ie, one HARQ process for one subframe of one RTT. There is more than one active HARQ process for UL and DL in any given subframe, but there is at most one UL and one DL HARQ process for each CC.

When referred to hereinafter, the term "Primary Component Carrier (PCC)" includes, without loss of generality, the carrier of a WTRU configured to operate multiple component (NAS) Information Acquisition) is only applicable to this component carrier. A WTRU may be configured with at least one PCC for DL (DL PCC) and one PCC for UL (UL PCC). Accordingly, a carrier that is not the WTRU's PCC is hereinafter referred to as a secondary component carrier (SCC).

The DL PCC may, for example, correspond to the CC used by the WTRU to obtain initial security parameters upon initial access to the system. The UL PCC may, for example, correspond to a CC where PUCCH resources are configured to carry all HARQ A/N and channel state information (CSI) feedback for a given WTRU.

A WTRU's cell typically includes a DL CC, optionally combined with a set of UL resources, such as a UL CC. For LTE Release 10, the Primary Cell (PCell) consists of a combination of DL PCC and UL PCC. A secondary cell (SCell) for a WTRU multi-carrier configuration includes a DL SCC and optionally a UL SCC (ie, LTE Release 10 supports an asymmetric configuration where the WTRU is configured with more DL CCs than UL CCs). For LTE Release 10, a WTRU multi-carrier configuration includes one PCell, and up to five SCells.

With CA, a WTRU may simultaneously use multiple receiver chains in the RF front end. Supporting non-contiguous spectrum also means that the RF front end must be able to reject blocking signals between different parts of the spectrum.

One aspect of CA related to DRX is the allocation of WTRU power consumption among components of different transceivers and their respective start-up times. Another aspect is the impact of the number of configured SCells for the WTRU on power consumption, and on RF front-end reconfiguration. Activation and/or deactivation of one or more CCs requires a change in bandwidth and sampling rate for the RF front-end, resulting in no transmissions from and to the WTRU during periods (which can vary in the hundreds of microseconds to 2ms).

As mentioned here, activation of a CC (especially an SCC) typically involves a procedure in which a WTRU ensures that one or more of its transceivers are capable of targeting a PCell and possibly also a or multiple SCells, perform reception on the relevant DL CC and/or perform transmission on the relevant UL CC. This may include reconfiguration of the RF front end, as explained in the case of transitioning from a state other than the "active" state. Similarly, "deactivation" of a CC refers to a state in which the CC is not "active," with transitions from that state also having a similar meaning.

There is a difference between a change in DRX state and a change in active state for a given CC depending on implementation and power consumption, as well as requirements when performing the respective state transitions.

For a WTRU configured to operate with multiple CCs, PDCCH monitoring and/or PDSCH reception for the PCC is typically activated and may be managed by the DRX. PDCCH monitoring and/or PDSCH reception for configured SCCs is activated or deactivated, and can also be managed by DRX when activated.

When a WTRU operates with multiple CCs, it may support cross-carrier scheduling, ie, scheduling between carriers using the PDCCH. Monitoring of PDCCH may not be necessary in all configured and/or active carriers when cross-carrier scheduling is possible.

There are several different options when considering WTRU power savings and multi-carrier operation. In common DRX (reference) selection, the WTRU monitors PDCCH for all CCs (configured with PDCCH) in a subframe that is part of the DRX active time, which is the same for all CCs. In independent DRX selection, all DRX timers are used for each CC, and thus the WTRU monitors the PDCCH of each CC (with PDCCH configured) independently. In the fast activation or deactivation mechanism, SCells can be activated and deactivated individually by L1 (e.g., using PDDCH) or L2 (e.g., using MAC CE) signaling, and a single activation or deactivation command can activate or deactivate the service Subset of the district. This fast activation or deactivation mechanism can be used by itself or combined with common DRX or independent DRX selection.

If the WTRU is designed with a single RF front end, whenever a CC's transmission or reception is enabled or disabled, retuning of RF reception and transmission will affect the transmission of other CCs not included in the enabling or disabling. To minimize WTRU transmission and reception processing requirements, UL and DL CCs should be enabled only when needed to eliminate or minimize transmission and reception failures.

In order for a WTRU to support multi-carrier operation, i.e. for the WTRU to be configured with more than one CC in LTE Release 10 with CA, it is considered possible to perform RF retuning for activation or deactivation of at least one CC how to minimize WTRU power consumption. In conjunction with DRX mechanisms, the handling of RF front-end reconfiguration (eg, allowing CC activation and deactivation) is considered during periods when it is not possible for the network to schedule a WTRU. DRX active time is processed for each activated CC, i.e., subframes of WTRUs addressed by the network scheduler for transmissions are also considered, assuming SCCs are switched on or off (e.g., DRX) and/or (de)activated (e.g., may require reconfiguration of the RF front end) is possible for WTRU implementations.

The WTRU and the network must have coherent and synchronized observations of one or more CCs and one or more subframes where the WTRU monitors control signaling (eg, PDCCH). One question is which events govern the DRX active time for each CC, and whether it is possible for the WTRU to perform retuning of the RF front end.

A WTRU may detect certain scheduling activities during a given period to determine whether it can activate additional SCCs, or deactivate the currently active SCC. The scheduling activity may indicate, implicitly or explicitly, which subframes are available to perform the necessary adjustments, and during which periods the WTRU is not expected to receive control signaling for the affected CCs.

It is desirable to ensure that the WTRU and the network remain synchronized with respect to UL timing and HARQ status. This synchronization includes handling time alignment when reconfiguring the RF front-end (e.g., performed in order to (de)activate the CC), which may introduce a larger drift than the WTRU needs to still be considered to have proper UL timing alignment drift. The synchronization also includes handling the HARQ state during scheduling gaps, ie, during times when it is not possible for the network to schedule the WTRU.

The WTRU may determine whether proper UL synchronization must be obtained upon RF retuning. The WTRU may determine the appropriate HARQ state in a given subframe in which there is at least one active HARQ process when the WTRU cannot receive (e.g., PDCCH, PHICH) or transmit (e.g., PUCCH ) control signaling.

Retuning transmission or reception failures may be minimized or eliminated by delaying enabling and/or disabling CCs until transmission or reception idle periods can be predicted by the WTRU or coordinated by the eNB. The enabling and/or disabling of CCs is determined by explicit or implicit methods to coordinate between the WTRU and eNB for known time periods, called retuning gaps.

In general, for each of the proposed methods, after a CC enabling and/or disabling trigger event, the WTRU determines the earliest time to minimize and in some cases eliminate transmit or receive failures on other CCs not affected by the enabling and/or disabling. Retune gap timing. Preferably, the retuning gap determined by the WTRU is known to the eNB so that the eNB can take further actions to eliminate transmission or reception failures.

The WTRU's automatic determination of retuning gap opportunities may be initiated from explicit signaling received from the eNB, or implicitly based on triggering events detected by the WTRU. The eNB may send explicit signaling requesting activation and/or deactivation of one or more CCs. The eNB signaling can be a PHY PDCCH order, a MAC control element or an RRC configuration message requesting to enable and/or disable one or more CCs. Upon receiving the eNB request, the WTRU determines the next retuning gap opportunity according to one of several methods described below.

Activation or deactivation may be implicitly triggered by the DRX state of one or more configured CCs. If each configured CC or subset of configured CCs has an independent DRX state that is mutually exclusive with respect to other CCs, a change in the DRX state of any one CC or subset of CCs will cause the WTRU to initiate the next retuning gap opportunity Automatically determined. If all configured CCs have a common DRX state, the change of the common DRX state will also lead to the determination of the next retuning gap opportunity.

During a WTRU active transmit or receive state on any configured CC, the WTRU may delay enabling and/or disabling of any CC until an inactive transmit or receive state is determined on all configured CCs that allow for a retuning period. Alternatively, the WTRU may track respective UL and DL transmissions and retransmissions on all enabled CCs to determine when there are retuning gaps that minimize and potentially eliminate failures during retuning periods sending or receiving.

The eNB also considers knowing one or more automatic methods used by the WTRU to determine retuning gaps and when CC activation and/or deactivation has been triggered to avoid initiating new transmissions and retuning gaps during known retuning gap periods. pass.

If explicit signaling and/or implicit events trigger the need to enable or disable one or more CCs, the enabling or disabling of CC transmission or reception is performed in the next retuning gap.

More than one enabling and/or disabling trigger event may occur before the WTRU determines that a retuning gap has occurred. When multiple trigger events occur, the events are added, but the event received later takes precedence. If different subsets of CCs experience triggering events, the combined higher-level set (superset) is affected when a retuning gap occurs. It is also possible that some or all triggered CC trigger events are cleared. For example, if an enabled CC has a disable event followed by an enable event, the trigger event may be cleared. If all detected trigger events are cleared by subsequent trigger events, then the retuning gap determined by the WTRU is canceled and normal transmission and reception may continue over the previously scheduled retuning gap period.

Transmissions not directly associated with PUSCH and PDSCH transmissions may also be considered when the WTRU determines the next available retuning gap. For example, the following may otherwise preclude WTRU-determined retuning gap opportunities: any PUCCH transmission (i.e., for periodic CQI, PMI, or RI); any periodic or aperiodic requested SRS transmission; ongoing RACH procedure, as long as MSG1-4 is not interrupted; paging occasion; or system information reception.

Transmissions and retransmissions are known to the WTRU, and the WTRU may make automatic retuning gap decisions based on this knowledge. New UL transmissions are known in advance based on four transmission time intervals (TTIs) ahead of PDCCH reception. UL retransmissions can also be known in advance by four TTIs ahead of HARQ feedback or PDCCH scheduling. DL retransmissions may also be approximated from feedback generated by the WTRU at least eight TTIs earlier than the earliest retransmission of the HARQ process.

In these cases, the WTRU may determine when idle periods may occur to apply retuning procedures for activation and/or deactivation of any subset of available CCs to avoid interrupting ongoing transmissions. The WTRU may track transmission and retransmission opportunities on all configured UL and DL CCs. The WTRU determines the retuning gap when a common idle period greater than or equal to the required retuning period duration is found on all CCs.

4A is a flowchart of a method 400 for a WTRU to determine retuning gap opportunities. A CC trigger event occurs (step 402), and the WTRU determines a retune gap opportunity (step 404) upon detection of an idle period at least as long as the required retune period.

The WTRU initiates the retuning gap determination procedure following a CC enable and/or disable event. This event may arise from explicit signaling received from the eNB and/or based on internal WTRU procedures (ie, independent DRX) that also result in one or more CCs being enabled or disabled. If an independent DRX process per CC or CC subset is applied by aligning the start of the DRX on quasi-duration, it may sometimes be possible to avoid the enable delay when no CC is currently active.

It is currently impossible for a WTRU to predict when an eNB will initiate a new DL transmission. But the eNB is aware of the CC enable and/or disable trigger events, as well as the WTRU logic for determining the next available retuning gap. When the retuning procedure is applied, the eNB may use this knowledge to avoid scheduling new DL transmission opportunities during the WTRU's determination of the retuning gap.

One method used in conjunction with this WTRU automatic retuning gap decision method is for the eNB to control or enforce when the gap is determined so that the eNB can determine in advance when new initiated transmissions should be avoided. Based on the connection to the WTRU retuning gap determination procedure, the eNB may idle one or more consecutive HARQ processes so that the eNB may predict the WTRU retuning gap in advance.

Another approach, which does not require the same fast WTRU processing, is to wait for the completion of any ongoing UL and DL HARQ process transmissions and retransmissions on all CCs. The WTRU makes the automatic retuning gap decision after a HARQ process transmission cycle. If a CC enable or disable trigger event occurs and there are no ongoing UL and/or DL transmissions, the retuning procedure may be applied immediately. If there are ongoing transmissions, the WTRU waits for all UL and DL HARQ process transmissions and retransmissions to make a decision to determine the retuning gap and apply the retuning procedure.

4B is a flowchart of a method 420 for performing retuning after an active HARQ process has ended. A CC trigger event occurs (step 422), and a determination is made whether there are any ongoing UL or DL transmissions (step 424). If there are no ongoing UL or DL transmissions, the WTRU applies a retuning procedure (step 426). If there are ongoing UL or DL transmissions, the WTRU waits for all HARQ transmissions and retransmissions to complete (step 428) before applying the retuning procedure (step 426).

The WTRU retuning gap for enabling or disabling CCs may be automatically determined by the WTRU when all ongoing HARQ process transmissions have been completed in both the UL and DL directions. For UL transmissions, the criteria for determining the retuning gap are met when either positive ACKs have been received for all ongoing UL HARQ process transmissions on all UL CCs or the maximum number of HARQ retransmissions has been exceeded for each HARQ process.

For DL transmissions, the criteria for determining the retuning gap are met when all ongoing DL HARQ processes have generated positive ACKs. The DL transmission criterion is also satisfied if the WTRU knows the maximum number of HARQ process retransmissions, or there are no initiated DL retransmissions after a known period of time. The retuning process is applied when the UL and DL retuning gaps are met. The HARQ process transmission and/or reception may then resume immediately after the retuning gap, as long as DRX criteria allow reception at that point (eg, if DRX on-duration, inactivity or retransmission timers are still active).

Furthermore, the idle time during which no new UL and/or DL transmissions are initiated is considered from the end of the most recent previous active transmission or retransmission before applying the retuning procedure. The idle period allows the eNB to stop initiating any new transmissions and enables the WTRU to reliably adjust the retuning period so that new initiating transmissions are not aborted. This idle period can be shorter than existing DRX inactivity and retransmission timers because CC enablement and/or deactivation events are known to the eNB and newly enabled transmissions can be stopped by the eNB. Once the retuning procedure is complete, eg in one or two TTIs, normal transmission and reception resumes depending on DRX criteria (ie if inactivity or retransmission timer has expired). Alternatively, for simplicity (albeit at the cost of some efficiency), this idle time can coordinate a combination of existing DRX inactivity and retransmission timers.

Another method for the WTRU is to wait for the DRX active time on all configured and enabled CCs to expire in order to determine the retuning gap and initiate the retuning procedure. If a CC enable or disable trigger occurs and no configured CCs are running within the DRX active time, the retuning process can be applied immediately. If any CC is operating during the DRX active time, the WTRU decision to retune the gap is delayed until the DRX active time on all configured CCs expires.

4C is a flowchart of a method 440 for performing retuning after DRX active time expires. A CC trigger event occurs (step 442), and a decision is made whether the DRX active time has expired (step 444). If the DRX active time has not expired, the WTRU waits until the DRX active time has expired. Once the DRX active time expires, the WTRU applies the retuning procedure (step 446).

Regardless of whether the CC enable and/or deactivate criteria are explicit activation or deactivation or DRX events (timers), the WTRU performs retuning at known retuning intervals or at expiration of DRX active time.

With independent DRX, the active time needs to be terminated on each configured CC for the WTRU to automatically determine the retuning gap. If, for example, CC independent DRX is used, and a newly configured CC is used as an explicit trigger for enabling the CC, then the WTRU auto-retuning gap is determined by waiting for active time to expire on all other CCs. Similarly, if the expiration of active time on the respective CC is used as an implicit trigger for disabling the CC, the WTRU auto-retuning gap is determined by waiting for the active time to expire on all other CCs.

If extended period transmissions occur, the eNB may force a retuning gap by delaying scheduling and potentially sending a MAC CE requesting the WTRU to enter DRX. In this case, the best option is to enter DRX immediately before the start of the next DRX On-Duration period to allow the transmission to restart quickly. One option is to enable or disable CC events to automatically force a retuning gap before the next on-duration period.

The eNB may pre-configure periodic retuning gap opportunities or may dynamically request retuning gaps to occur at specific times. The pre-configured retuning gap is just timing. These cycles are available for transmission and reception if the retune trigger event does not occur before the next retune gap occasion or if the trigger event is canceled by a subsequent trigger event.

Periodic retuning gap timing relative to the cell's System Frame Number (SFN) can be configured. After a retune trigger event, the next available retune gap occasion may be selected. Triggering events may be: an explicitly notified MAC Control element, an independent DRX method per CC or a subset of CCs, and/or a WTRU requesting or notifying permission to enable and/or disable transmission and reception on one or more CCs RRC configuration process. When no trigger event has occurred since the most recent retune gap occasion, reception is not restricted during subsequent retune gaps. Periodic retuning gap periods may be aligned by DRX cycle configuration.

Alternatively, the eNB may dynamically identify to the WTRU when retuning is applied. The coordination of the exact period can be based on PHY (PDCCH) or MAC signaling. After one of the previously described trigger events, the WTRU may wait for the eNB to dynamically allocate retuning gaps. If dynamic retuning gaps are used, the retuning period may also be identified by the eNB signal enabling or disabling one or more CCs.

The eNBs may use explicit signaling to coordinate when to apply the WTRU retuning procedure. A configurable periodic cycle can be configured for retuning opportunities, or aperiodic requests can be used to dynamically allocate retuning gaps.

A known periodic cycle for retuning gaps may be known to the WTRU where the WTRU has the opportunity to enable and/or disable CC transmission or reception. Known periodic retuning gaps may be used to enable and/or disable CCs based on implicitly triggered or explicitly signaled retuning events. Known periodic cycles may be configured separately, or implicitly aligned, or associated with configured periodic DRX cycle configurations. Implicit or explicit retuning events are known to the WTRU and eNB, so the use of the next periodic retuning period is known. When a retune trigger event does not occur before the known retune gap, normal transmit and receive operations continue during periods in which the retune process is not performed.

When the WTRU has automatically determined the retune trigger criteria (ie, independent DRX), the retune gaps may be allocated dynamically by eNB signaling. Dynamically allocated retune gaps can also be coordinated using CC enable and/or disable trigger events at known times from the trigger event or by sending a specific retune gap period with a new number.

An indirect method is for the eNB to idle inter-CC transmissions to force one of the WTRU's automatic methods to determine retuning gaps in time periods known to the eNB. This can be done by idling one or more consecutive HARQ processes that are aligned across the configured set of CCs.

For the eNB periodically configured or dynamically allocated retuning gap approach, ongoing HARQ process transmission and reception can be designed to skip HARQ transmission and reception opportunities. In this case, the HARQ process will skip the retransmission opportunities masked by the eNB that allocated the retuning gap. The transmission itself is skipped, or an unsuccessful ACK is assumed for that transmission. With this approach, loss of eNB scheduling opportunities is minimized. New transmissions can be scheduled at any time other than the actual retuning gap period, since retransmission opportunities do not have to be considered.

Although the following embodiments describe scheduling gaps based on 3GPP LTE technology and related specifications, these embodiments are also applicable to any multi-carrier technology implementation method for activating or deactivating CCs, and/or methods generally used for battery saving, such as Other 3GPP technologies based on WCDMA, HSPA, HSUPA or HSDPA.

A WTRU may be configured with at least one SCell for multi-carrier operation, eg, for an LTE Release 10 WTRU. Multi-carrier operation may be scheduled using control signaling of certain features during the first period during which the WTRU is able to determine whether a second period occurs. During the second period, the WTRU is not expected to be active for transmission on the carrier affected by the WTRU transceiver state change.

In one example, a WTRU configured with at least one SCC successfully decodes at least one PDCCH on its PCell during the first period. If there is a WTRU not in the second period of DRX active time, the second period is at least as long (in subframes) as the time the WTRU needs to activate at least that WTRU's configured first SCell that was inactive during the first period unit), then the WTRU may activate the first SCC so that the WTRU may transmit according to the control signaling received in the third period. In this example, the first and third cycles correspond to consecutive DRX cycles, while the second cycle corresponds to subframes within (and near the end of) the first cycle.

Existing DRX principles are modified to allow the WTRU to switch off part of the transceiver circuitry or implicitly deactivate one or more CCs (e.g., one or more SCells) when possible (e.g., possibly including retuning the RF front-end ). This is based on a deterministic rule set to maintain a coherent observation between the network scheduler and WTRU behavior. A scheduler implementation can generate a scheduling gap that can be interpreted by the WTRU as a possibility to retune its RF front end.

The baseline DRX operation for an LTE Release 10 WTRU may be that when only the PCell is active, the WTRU follows the LTE Release 8/9 DRX behavior corresponding to DRX active time. When at least one SCell is configured or activated (e.g., using RRC), all CCs of the WTRU follow a common DRX active time, possibly according to Release 8/9 DRX (based on the primary DRX active time (PDAT), or according to each individual CC's DRX Active Time (DAT) sum), or a simplified version thereof, as described above.

DRX active time and/or active state of CCs may be common to CCs within the same frequency band. The benefit of this is that DRX transitions and/or RF retuning performed for one or more CCs of the same frequency band (i.e., the same RF front end) may not require any scheduling gaps for CCs of a different frequency band (i.e., different RF front ends) .

In particular, if combined RRC configuration and activation of SCells are used, the same active time may apply for CCs in the same frequency band, meaning that not all CCs follow the same active time for a given WTRU.

The following terms used herein are defined as follows.

PDCCH position: refers to the DL CC on which the PDCCH is successfully decoded.

PDCCH target: when using cross-carrier scheduling, refers to the CC for which the PDCCH provides control information, for example, the UL CC in the grant case or the DL CC in the allocation case.

Primary DRX Active Time (PDAT): includes the subframe for which the WTRU monitors the PDCCH for allocations and/or allocations applicable for transmission on the PCell, ie PDAT corresponds to the DRX Active Time considering only the PCell. One or more applicable PDCCHs may be characterized as using PDCCH positions as PCells, PDCCH targets as PCells, or both.

Scheduling gaps: include subframes where the WTRU is not expected or cannot transmit or receive on at least one CC. For example, this may include at least one of: PDCCH monitoring for DL allocations and/or UL grants applicable to transmissions on CCs; Physical HARQ Indicator Channel (PHICH) reception for one or more HARQ processes; or PUCCH transmission, e.g. for HARQ A/N feedback of one or more HARQ processes.

Scheduling gaps (i.e. RF Retune (RFR) gaps or DRX State Transition (ST) gaps) can be specifically excluded from events during DAT, i.e. subframes that are part of a scheduling gap can be explicitly excluded from DAT . Alternatively, scheduling gaps may be allowed as part of DAT. In the latter case, the WTRU is not required to monitor the PDCCH during the scheduling gap even though it occurs during DAT, similar to the measurement gap in Release-8.

A scheduling gap may be the result of a change in the set of active CCs (or SCells), eg, as a result of "activation" and/or "deactivation" of at least one CC (or SCell), requiring the WTRU to retune the RF front end. The retuning process may impair WTRU transmissions for a period of time (eg, may be 1 ms or 2 ms), also referred to as an RFR gap. Activation or deactivation may be the result of explicit signaling (eg, RRC signaling, MAC signaling, or L1/PDCCH signaling) or implicit signaling (eg, time-based) from the network.

The scheduling gap may also be the result of DRX state transition after the DRX active time of the CC set changes. At least one CC may be maintained during DRX active time, which does not require the WTRU to retune its RF front end. But this CC requires turning on or off several functional blocks, e.g. functional blocks before the RF front end (transmit) or after the RF front end (receive), but impairs the WTRU transmission for a period of time (e.g. could be 1 ms or 2 ms), And may be referred to as DRX ST gap.

Thus, the scheduling gap is a fixed value (eg, 1 ms or 2 ms), a network configurable value, a value derived from WTRU performance (possibly including WTRU processing time), or a value derived based on whether the gap is an RFR gap or a DRX ST gap.

An "active period" is defined as a number of consecutive subframes during which, for at least a subset of subframes of the active period, the WTRU monitors the PDCCH of at least one DL CC (e.g., PCell) during the DRX active period to obtain DL assignments and/or UL grants for transmissions on the active CC. The active period may consist entirely of subframes in which the WTRU is in DAT, e.g., when the period is equal to the DRX On-Duration period; or may consist of subframes in which the WTRU is not in DAT (i.e., one or more periods of inactivity), For example, when the period is equal to the DRX cycle. The term "applicable", when used in conjunction with a PDCCH (e.g., "PDCCH applicable to a CC"), refers to at least one of: a PDCCH target of a UL and/or DL CC as a subgroup, a CC as a subgroup PDCCH position, or both.

An activation period may be used as a set of subframes during which the detection of one or more DL assignments and/or one or more UL grants applicable to a CC results in a DL assignment and/or UL assignment for the same CC or a different CC Subsequent activation of authorized PDCCH monitoring. The activation period may precede a scheduling gap. There may also be a scheduling gap (and one or more periods of inactivity) after the active period, if the length of the active period is different from the length of the multi-CC DRX cycle. "Period of inactivity" means that the WTRU is not required to monitor the PDCCH for assignments and/or grants applicable to transmissions on at least one CC according to DRX rules.

A "multi-CC DRX cycle" is defined as a periodic repetition of an active cycle, i.e., an active cycle occurs once on each multi-CC DRX cycle, as shown in Figure 5. In an alternative embodiment, the activation period may be shorter than the PDCCH monitoring activity.

The description of the following embodiments is based on the "activation" and "deactivation" of the CC according to the retuned RF front-end, and therefore uses the term RFR gap. These embodiments are equally applicable to DRX state transitions that do not require retuning of the RF front end (hence the term "scheduling gap" may be used instead), or to combinations of DRX state transitions and CC activation or deactivation.

The following embodiments use at least one of the following principles: CC grouping, determining whether RF retuning should be performed, determining that one or more SCCs should be activated, or determining the timing of RFR gaps.

Using CC grouping, the set of CCs for a WTRU's multi-carrier configuration may be conceptually separated into subgroups. For example, one or more PCCs for which the WTRU monitors PDCCH according to PDAT; or one or more SCCs for which the WTRU monitors PDCCH according to DAT, if DAT is configured or possibly also activated. This definition does not exclude cases where all CCs are processed individually, all SCCs are processed as a single subgroup, SCCs of the same frequency band are all processed as subgroups, or PCCs are further grouped into PCells and SCCs are grouped into SCell.

The decision whether RF retuning should be performed is made during the active period. The active period is used to determine at least one of: (1) whether an RFR gap is available to the WTRU at a particular point in time during a multi-CC DRX cycle (ie, on a period of the active period). (2) Whether an SCC (or multiple SCCs) is active after the RFR gap occurs. For example, how the WTRU may reconfigure the RF front end, ie which SCC (or SCCs) may be activated during RF retuning, or for which CC (or CCs) the WTRU may monitor the PDCCH after the RFR gap. (3) Whether the active CC set can be modified based on events that occur during the activation period.

The decision which SCC (or SCCs) can be activated is made during an activation period. The activation period is used to determine whether an SCC (or SCCs) can be activated based on at least one of the following: (1) If the WTRU did not successfully decode any PDCCH during the activation period, then only the CC corresponding to the PCell is active. (2) If the WTRU successfully decodes the PDCCH applicable to the PCC during the activation period, then all CCs are active. (3) A SCC (or corresponding subgroup of SCCs) is active if the WTRU successfully decodes the PDCCH applicable to the SCC (or SCCs) during the activation period.

For example, if a WTRU is scheduled on at least one SCC of a subgroup of SCCs during the activation period, the DAT and PDAT of the subgroup follow a common pattern during the period after the activation period. Otherwise, DAT for the subgroup of SCCs follows a different pattern (eg, the WTRU does not actively monitor PDCCH for the subgroup of CCs), and/or deactivates the subgroup of CCs during RFR gaps.

Determining the timing of the RFR gap includes determining whether the RFR gap is included before the next activation period or after the current activation period.

The RFR gap immediately precedes the next active cycle if at least one of the following is true. (1) One or more CCs of at least a subgroup of one or more CCs are inactive in the subframe corresponding to the first subframe after the activation period minus the RFR gap length. (2) If at least one PDCCH was successfully decoded by the WTRU during the current activation period. This can be further restricted by additional conditions, such as: in the case of PDCCH applicable to PCell, in the case of PDCCH applicable in SCell, or in the case of PDCCH applicable in SCell and in the case of SCell activated Down.

If the WTRU determines during the activation period that a different set of CCs can be activated after the activation period, it may only be used for the margin of the current multi-CC DRX cycle, e.g. if the two periods are different, the RFR gap immediately follows the current activation period .

Using the above principles, implementations can be implemented that define the length of the multi-CC DRX cycle, the length of the active cycle, and the parameters of the RFR gap. The length of the multi-CC DRX cycle is equal to the DRX cycle used by the WTRU (long DRX cycle or short DRX cycle, if configured), or a configurable time period different from the configured DRX cycle length. The length of the active period is equal to one of: the length of the DRX on duration, the subframe during which the WTRU is in DRX active time (eg, PDAT), or the length of the multi-CC DRX cycle.

The RFR gap may be a fixed value (eg, lms or 2ms), a value configurable by the network, or a value derived from the WTRU's capabilities (possibly including WTRU processing time). The presence, and possibly length, of the RFR gap may be explicitly signaled to the WTRU by the network, eg in a MAC CE, including possibly reusing an LTE Release 8/9 DRX MAC CE or similar. The MAC CE may additionally include an indication of which subframe corresponds to the start of the RFR gap (either as an offset from the start of reception of the MAC CE, or as a feedback sent for a received HARQ acknowledgment of the MAC CE, or as an absolute value, e.g. in DRX loop), and its duration. The MAC CE also includes signaling for activating or deactivating one or more SCCs or SCells.

The above principles may be used in the case of defining a single SCC group that includes all SCCs configured by the WTRU. These principles can also be used in cases where the PCell's CCs remain active while at least one SCC is activated simultaneously, and follow a specific DRX pattern similar to Release 8/9 DRX or a simplified version thereof.

In the embodiments described below, a number of subframes corresponding to WTRU processing time for PDCCH signaling may be additionally inserted before an RFR gap may occur (ie, before or after the activation period) to allow the WTRU to determine whether an RFR gap is required. During these subframes, the WTRU may not consider a successfully decoded PDCCH to be part of the logic for determining whether an RFR gap is required.

Variations may include: using different DRX on-durations for the PCC and one or more SCCs, where the activation period corresponds to the DRX on-duration period for the one or more SCCs; using PDCCH control signaling (grant or allocation), as an explicit signal that a CC (or the corresponding SCell, or all SCCs if possible at once) can be activated after the end of the activation period; or a multi-CC DRX cycle configured by upper layers (e.g., RRC), so that it is An integer multiple of the DRX cycle used by the WTRU.

To handle UL timing alignment, if the WTRU is not concerned about maintaining UL synchronization after RF front-end retuning (due to, for example, a change in one or more active SCell sets), then the WTRU may additionally be required to perform a procedure to regain time alignment.

In order to handle HARQ processes, scheduling requests, and transmit HARQ feedback, CQI, PMI or RI, and SRS, the WTRU may additionally implement certain logic to ensure that the relevant state remains correlated with the state of the eNB.

The WTRU may include the RFR gap in the subframe starting from the end of the multi-CC DRX cycle minus the length of the RFR gap (if the WTRU determines that not all CCs are active in the subframe).

The WTRU may use an activation period equal to the length of the configured and currently active multi-CC DRX cycle, i.e. which SCC (or SCCs) are required in the subsequent multi-CC DRX cycle is based on the PDCCH activity of the multi-CC DRX cycle immediately preceding it determined by sex.

Similarly, the WTRU may use a multi-CC DRX cycle equal to the current DRX cycle based on the WTRU configuration for the long DRX cycle and the short DRX cycle (if configured). The release 8/9 mechanisms for cyclic transitions can still be used, including DRX MAC CE.

Figure 6 is a timing diagram 600 where the active period has the same length as the DRX cycle. The WTRU performs at least one of the following.

No later than the subframe corresponding to the last subframe of the current DRX cycle minus the RFR gap length, an RFR gap is required if the WTRU determines that it can monitor a CC set different from the current active set of CCs during the next DRX cycle. The WTRU considers the remainder of the DRX cycle (ie, a number of subframes equal to the RFR gap length) to be an opportunity to retune the RF front end and/or change the activation state of the SCC (step 602).

In subframes corresponding to RFR gaps (if required by previous steps), the WTRU reconfigures the RF front end and/or activates the SCC according to at least one criterion for activating the SCC (step 604).

The WTRU starts a new DRX cycle. In subframes of the DRX cycle, the WTRU monitors PDCCHs applicable to all CCs configured or activated during DAT (possibly like PDAT) except the subframes that are part of the RFR gap (steps 606, 608).

The WTRU determines whether at least one PDCCH applicable to any CC (ie, for PCell or any SCell) has been successfully decoded in any subframe of the cycle. If there is no need to perform retuning of the RF front end and/or change the activation state of the SCC, then the WTRU determines that no RFR gap is needed. For example, in the case that no PDCCH is successfully decoded and no SCC is activated for the current DRX cycle, or at least one PDCCH is successfully decoded and all configured SCCs are activated for the current DRX cycle.

The WTRU may also determine if no successfully decoded PDCCHs were applicable to the SCC during the DRX cycle (ie, only PDCCHs applicable to the PCell were received).

The WTRU may also determine whether at least one PDCCH applicable to a SCC (in particular, a CC that is a PDCCH target) was successfully decoded in any subframe of the DRX cycle. If there is no need to perform retuning of the RF front end and/or change the activation state of the SCC, the WTRU determines that no RFR gap is needed. For example, when no PDCCH is successfully decoded and no SCC is activated for the current DRX cycle, or at least one PDCCH is successfully decoded, but all PDCCHs are only applicable to one or more SCCs configured to be activated for the current DRX cycle Down.

The WTRU may additionally determine an SCC (or multiple SCCs, possibly a subset of SCCs) to which the PDCCH applies. In this case, only the SCCs corresponding to one or more subgroups will remain active for the remainder of the current DRX cycle.

The WTRU determines whether an RFR gap is required based on at least one of the following. If no PDCCH is successfully decoded, only the CC corresponding to the PCell needs to be used for the next DRX cycle. The RFR gap is only required when at least one SCC is active for the current DRX cycle, if no successfully decoded PDCCH is applicable to any SCC of the corresponding SCell, or if the PDCCH indicates a new transmission.

If at least one PDCCH applicable to the SCell is successfully decoded, an RFR gap is required only if the SCC(s) active for the current DRX cycle is different from the SCC(s) that should be active for the next DRX cycle , possibly only considering the PDCCH indicating a new transmission.

In the subframes before the start of the next DRX cycle (number of subframes equal to the number of subframes of the RFR gap), the WTRU reconfigures the RF front end and/or activates the SCC if the WTRU previously determined that an RFR gap is required (step 610). Reconfiguring the RF front end or activating the SCC is based on the criteria of whether the activation state of the CC can be modified. The WTRU may reconfigure the RF front end and/or: deactivate all SCCs, activate all SCCs, or only deactivate SCCs (or a subset thereof) of applicable PDCCHs that were not successfully decoded during the DRX on-duration.

During the entire DRX cycle, the WTRU applies the same DRX active time for all CCs (eg, PDAT) for which the WTRU monitors the PDCCH applicable to transmissions on one or more CCs (eg, all activated CCs). The WTRU does not need to monitor the PDCCH for other CCs (e.g., conceptually, use a different DRX active time than PDAT, or alternatively, consider the CC to be deactivated and not be affected by DAT), which in addition may be in the previous RFR The interstitial period has been deactivated.

The WTRU may include an RFR gap after the activation period if the WTRU determines that a different set of CCs on which the PDCCH may be received during the activation period may be used during the remainder of the multi-CC DRX cycle. Alternatively, the WTRU may include the RFR gap in the subframe starting from the end of the multi-CC DRX cycle minus the RFR gap length (if the WTRU determines that not all CCs are activated in that subframe).

The WTRU may use an active period equal to the configured DRX on-duration period, ie the start point of each period is equal to the length of the period. Similarly, the WTRU may use a multi-CC DRX cycle equal to the current DRX cycle based on the WTRU configuration for the long DRX cycle and the short DRX cycle (if configured). Release 8/9 mechanisms for cycle transitions can still be used, including DRX MAC CE.

FIG. 7 is a timing diagram 700 where the active period has the same length as the DRX on-duration. The WTRU performs at least one of the following.

For the subframe corresponding to the nearest subframe of the current DRX cycle minus the RFR gap length, if the WTRU determines that the number of active SCCs in the subframe is less than the total number of configured SCCs, an RFR gap is required. The WTRU considers the remainder of the DRX cycle as an opportunity to perform retuning of the RF front end and/or change the activation state of the SCC (step 702).

In subframes corresponding to RFR gaps (if required by previous steps), the WTRU reconfigures the RF front end and/or activates all SCCs (step 704).

The WTRU starts a new DRX cycle. In subframes corresponding to the on-duration period (ie, while the DRX on-duration timer is running), the WTRU monitors the PDCCH applicable to all configured CCs (step 706).

The WTRU determines whether at least one PDCCH applicable to any CC (ie, for PCell or any SCell) was successfully decoded in any subframe of the period, in which case the WTRU determines that no RFR gap is required.

The WTRU determines if no successfully decoded PDCCHs are applicable to the SCC during the period (ie, only PDCCHs applicable to the PCell are received).

The WTRU determines whether at least one PDCCH applicable to the SCC was successfully decoded in any subframe of the period, in which case the WTRU determines that an RFR gap is required.

The WTRU may also determine to which SCCs (possibly subgroups of SCCs) the PDCCH is applicable, in which case only the SCCs corresponding to one or more subgroups will remain active for the remainder of the current DRX cycle.

The WTRU determines whether an RFR gap is required based on at least one of the following. If no PDCCH is successfully decoded, only the CC corresponding to the PCell is required for the remainder of the DRX cycle, and an RFR gap is required. RFR gaps are also required if a PDCCH that is not successfully decoded is applicable to any SCC corresponding to the SCell, or if the PDCCH indicates a new transmission.

If at least one PDCCH applicable to the SCell has been successfully decoded, or if the PDCCH indicates a new transmission, no RFR gap may be required. However, in cases where the WTRU may reconfigure the RF front end and/or may deactivate one or more SCCs (or a subset thereof) for which no successfully decoded PDCCHs are applicable, RFR gaps may be required, thereby The resulting number of active SCCs for the remainder of the DRX cycle will be less than the number of active CCs during the on-duration period.

Beginning at the first subframe after the end of the DRX on-duration period, the WTRU configures the RF front end and/or activates the SCC if the WTRU previously determined that an RFR gap is required (step 708). The WTRU may reconfigure the RF front end and/or: deactivate all SCCs or only SCCs (or a subset thereof) for which no applicable PDCCH has been successfully decoded during the DRX on-duration.

During the remainder of the DRX cycle, i.e., after the end of the DRX-on-duration, the WTRU applies the same DRX active time for one or more all CCs (e.g., PDAT) for which the WTRU monitors applicable or PDCCH for transmission on multiple CCs, eg, all activated CCs (step 710). The WTRU does not need to monitor the PDCCH (eg, different DRX active time than PDAT) for other CCs that may have otherwise been deactivated during the previous RFR gap. In addition, the WTRU performs step 702 above.

During the RFR gap at the end of the DRX cycle, the WTRU reconfigures the RF front end and/or activates all SCCs (step 712).

Conceptually, some of the above options can also be seen as PCC after the first DRX active time (e.g. PDAT that may follow Release 8/9 DRX guidelines), and SCC at the second DRX active time (e.g. SDAT) after. During the DRX on-duration period, the SDAT is the same as the PDAT for all SCCs. If the WTRU determines that at least one SCC has not been scheduled, the WTRU's SDAT (possibly all) may deactivate (i.e., enter DRX sleep or deactivate state) one or more SCCs after a gap occurs during which no It is desired to schedule the WTRU. If the WTRU has determined during the DRX on-duration that at least one SCC should not be after the PDAT for that period, then the WTRU inserts a similar gap in the DRX mode towards the end of the DRX cycle.

The WTRU may perform required measurements for the configured SCells during the activation period according to specific measurement requirements. The measurements may be CQI measurements (if configured, such as, for example, A1/A2 threshold-based measurements on SCells), or RRC configured measurements such that the WTRU may independently report one or more configured SCells for the SCell Is active throughout the multi-CC DRX cycle.

The existence of scheduling gaps may be caused by WTRU implementations or synchronization methods. When implemented on a WTRU basis, the WTRU automatically determines when a scheduling gap occurs in which case the timing of the gap is not known to the eNB scheduler. Based on this situation, there are ongoing HARQ processes that need to be processed during the scheduling gap, therefore, there should not be any ongoing transmissions during the scheduling gap.

When based on a synchronization method, scheduling gaps can be scheduled by explicit signaling from the eNB or by an implicit method. The first implicit method is based on a timer or configured start offset and periodicity (the methods above would fall into that category). The second implicit method is based on the HARQ process state, eg, once all HARQ processes are completed, a gap may be scheduled.

In any of the above cases, if the gap occurs during an ongoing transmission, the HARQ process should not become in a state that is no longer coherent with the eNB state for one or more of the same HARQ process.

The WTRU may process the HARQ process for subframes that are part of the required scheduling gap in a similar manner to the measurement gap. This also applies to handling scheduling requests, and transmission of HARQ feedback, CQI, PMI or RI, and SRS.

When a WTRU initiates a random access procedure and the WTRU is required to use a scheduling gap, the WTRU may perform at least one of the following procedures to handle the random access procedure when it conflicts with the scheduling gap.

The WTRU may delay the transmission of the preamble if the subframes that are part of the schedule coincide with subframes that the WTRU has used for preamble transmission. For example, if the colliding subframe corresponds to the next available subframe, said next available subframe includes the constraints given by the prach configuration index, the PRACH mask index, and the physical layer timing requirements (similar to conflicting with measurement gaps) that allow PRACH, the WTRU may delay the transmission of the preamble.

If a random access preamble has been sent before the scheduling gap occurs, the WTRU may: extend the length of the RA response window, e.g., by an amount at least equal to the length of the scheduling gap; ignore the scheduling gap, so that the WTRU does not perform related actions , for example, RF front-end retuning and/or one or more DRX transitions; or determining that the random access procedure was unsuccessful.

If the WTRU has already received a UL grant in the RAR for a subframe that conflicts with the required scheduling gap, the WTRU may ignore the scheduling gap so that the WTRU does not perform related actions, such as RF front-end retuning and/or one or Multiple DRX transitions. Alternatively, the WTRU may ignore the received grant and declare the random access procedure unsuccessful.

If Msg3 has been sent, and if a scheduling gap occurs while the collision resolution timer is running, the WTRU may exclude one or more subframes that were part of the gap from the contention resolution period; i.e., do not update the timer for these subframes . Alternatively, the WTRU may ignore the scheduling gap such that the WTRU does not perform related actions, eg, RF front-end retuning and/or DRX transition.

The WTRU may perform procedures to restore UL time alignment after RF front-end retuning has been performed, which may be caused by certain events such as triggering a change in the active SCell set. The process may include any of the following.

The WTRU may consider the TAT terminated and perform related actions, eg, remove configured dedicated UL resources when performing RF front-end retuning. The WTRU may not necessarily remove some or all dedicated resources (eg, SRS, CQI).

The WTRU may send a dedicated preamble at the first possible opportunity after RF front-end retuning has been completed. Only the preamble is sent in this case, which allows the eNB to use a dedicated transmission on the DL SCH to send a Timing Advance Command (TAC) back to the WTRU, which then applies the received timing adjustments. The eNB may derive the WTRU's identity from a received dedicated preamble that has been previously assigned to the WTRU.

The WTRU may resume sending SRS on configured (ie, dedicated) SRS resources. The SRS transmission may then be used by the eNB to determine the timing adjustment needed by the WTRU. Alternatively, the WTRU may restart sending CQI on its configured (ie, dedicated) CQI resources. The CQI transmission may then be used by the eNB to determine the timing adjustments needed by the WTRU.

The WTRU may initiate RACH procedures, including initiating contention-free random access (CFRA) or contention-based random access (CBRA). The WTRU may also perform any other procedures that require RACH procedures.

Either of the above procedures may be combined with the additional requirement that the WTRU is not allowed to perform any UL transmissions (other than one or more of any transmissions required by the synchronization procedures above) until a TAC and/or RA Msg2 is received (ie, synchronization procedure complete), or until the WTRU successfully decodes the PDCCH to its C-RNTI (possibly only for DCI indicating UL grant).

Alternatively, the eNB may rely on UL transmissions from the WTRU based on normal operation and issue TACs to the WTRU if needed.

For LTE Release 8/9, once the WTRU has acquired the DL time using the primary and secondary synchronization channels, the WTRU should be able to synchronize each subframe to the DL time so that after the RF is tuned to a cell, WTRU oscillator drift is not an issue . This also applies to multiple cells sharing the same TA.

Example

1. A method for scheduling, by a wireless transmit/receive unit (WTRU), when a retune gap occurs, the method comprising: detecting a retune trigger event; if the trigger event is detected, determining that a retune gap occurs and performing radio frequency front-end retuning during the retuning gap.

2. The method of embodiment 1, wherein the retune trigger event is based on any of: an explicit signal received by the WTRU, or an implicit determination by the WTRU.

3. The method of embodiment 2 wherein the explicit signal received by the WTRU comprises a component carrier based activation or deactivation signal received from an eNodeB.

4. The method of embodiment 2, wherein the implicit determination of a retune trigger event includes a change in discontinuous reception status of one or more component carriers.

5. The method as in any one of embodiments 1-4, wherein the retuning gap period is determined based on uplink transmission or downlink transmission.

6. The method of embodiment 5, wherein the transmission is based on any of: physical downlink control channel reception, uplink hybrid automatic repeat request (HARQ) feedback, or downlink HARQ feedback .

7. The method of embodiment 6, further comprising determining an idle period having a length greater than or equal to a retuning gap length.

8. The method as in any one of embodiments 1-4, wherein the retuning gap period is determined based on the status of Hybrid Automatic Repeat Request (HARQ) process transmissions; and once all uplink and downlink HARQ processes idle, the retuning slot is determined where the HARQ process is idle if: the WTRU generates a HARQ acknowledgment, the WTRU receives a HARQ acknowledgment, or the maximum number of transmissions has been reached for all HARQ processes .

9. The method as in any one of embodiments 1-4, wherein the retuning gap period is determined based on idle periods detected from the end of previously active transmissions or retransmissions on all active component carriers.

10. The method of embodiment 9, wherein the retuning gap period is determined if the detected idle period has a length greater than or equal to the retuning gap length.

11. The method as in any one of embodiments 1-4, wherein the retuning gap period is determined based on a discontinuous reception (DRX) cycle.

12. The method of embodiment 11, wherein: in the case that all active component carriers are not within the DRX active time, and in the case that the length of time until the next DRX on-duration practice period is greater than or equal to the retuning gap length Next, determine the retuning gap.

13. The method of embodiment 12, wherein all activated component carriers are no longer within the DRX active time or within the required retuning gap period before the next DRX on-duration period or next DRX cycle In the case of , the determined retuning gap is applied.

14. A method performed by a wireless transmit/receive unit (WTRU) during an activation period, the method comprising: monitoring the physical downlink of at least one downlink (DL) CC for any CC from a set of active component carriers (CCs) Link Control Channel (PDCCH) to obtain channel assignments, and to determine whether radio frequency retuning (RFR) gaps are available to the WTRU during a multi-CC discontinuous reception (DRX) cycle. In case the CCs in the at least one CC subgroup are not active within the first subframe after the activation period minus the duration of the RFR gap, the method further includes scheduling the RFR gap to precede the next activation period. In case at least one PDCCH is successfully decoded by the WTRU during the active period, the method further includes scheduling the RFR gap to be before the next active period. Where a different set of CCs may be activated after an activation period, the method further includes scheduling RFR gaps to follow the activation period.

15. The method of embodiment 14, wherein in case the WTRU successfully decodes a PDCCH applicable to at least one component carrier (SCC), the method further comprises activating at least one SCC after an RFR gap.

16. The method of embodiment 14 or 15, wherein the duration of the multi-CC DRX cycle is equal to the duration of the DRX cycle used by the WTRU.

17. The method as in any one of embodiments 14-16, wherein the duration of the multi-CC DRX cycle is a configurable DRX cycle length.

18. The method as in any one of embodiments 14-17, wherein the duration of the activation period is any one of: DRX on duration, duration of main DRX active time, or duration of multi-CC DRX cycle time.

19. The method as in any one of embodiments 14-18 wherein the duration of the RFR gap is any one of: a fixed value, a value configured by the network, or a value derived from the capabilities of the WTRU.

20. The method as in any one of embodiments 14-19, wherein the channel assignment comprises at least one of a DL assignment or an uplink grant.

Although features and elements of the present invention have been described above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used alone without the other features and elements or in combination with the present invention The other features and elements of the invention are used in various combinations. In addition, the method provided by the present invention can be implemented in a computer program, software or firmware executed by a computer or a processor, wherein the computer program, software or firmware is contained in a computer-readable storage medium. Examples of computer readable media include electronic signals (transmitted over wired or wireless connections) and computer readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor storage devices, magnetic media such as internal hard disks and removable disks, Magneto-optical media and optical media such as CD-ROM discs and digital versatile discs (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC or any host computer.

Claims (20)

CLAIMS 1. A method for scheduling, by a wireless transmit/receive unit (WTRU), when a retuning gap occurs, the method comprising: detecting a retune trigger event; In the event that the triggering event is detected, determining a time period during which a retuning gap occurs; and Radio frequency front-end retuning is performed during the retuning gap. 2. The method of claim 1, wherein the retuning trigger event is based on any one of: an explicit signal received by the WTRU, or an implicit determination by the WTRU. 3. The method of claim 2, wherein the explicit signal received by the WTRU comprises a component carrier based activation or deactivation signal received from an eNodeB. 4. The method of claim 2, wherein the implicit determination of the retune trigger event comprises a change in discontinuous reception status of one or more component carriers. 5. The method of claim 1, wherein the retuning gap period is determined based on uplink transmissions or downlink transmissions. 6. The method of claim 5, wherein the transmission is based on any one of: physical downlink control channel reception, uplink hybrid automatic repeat request (HARQ) feedback, or downlink HARQ feedback . 7. The method of claim 6, further comprising: An idle period having a length greater than or equal to the retuning gap length is determined. 8. The method of claim 1, wherein: The retuning gap period is determined based on the status of the Hybrid Automatic Repeat Request (HARQ) process transmission; and The retuning gap is determined once all uplink and downlink HARQ processes are idle, where the HARQ processes are idle when: the WTRU generates a HARQ reply, the WTRU receives a HARQ reply, or for The maximum number of transmissions has been reached for all HARQ processes. 9. The method of claim 1, wherein the retuning gap period is determined based on detection of idle periods from the end of previously active transmissions or retransmissions on all active component carriers. 10. The method of claim 9, wherein the retuning gap period is determined if the detected idle period has a length greater than or equal to a retuning gap length. 11. The method of claim 1, wherein the retuning gap period is determined based on a discontinuous reception (DRX) cycle. 12. The method of claim 11, wherein: In case all active component carriers are not within the DRX active time, and In case the length of time until the next DRX On-Duration period is greater than or equal to the retuning gap length, a retuning gap is determined. 13. The method of claim 12, wherein all activated component carriers are no longer within the DRX active time or within the required retuning gap period before the next DRX on-duration period or next DRX cycle In the case of , the determined retuning gap is applied. 14. A method performed by a wireless transmit/receive unit (WTRU) during an activation period, the method comprising: Monitor the Physical Downlink Control Channel (PDCCH) of at least one downlink (DL) CC for any CC from the set of active component carriers (CCs) for channel assignment; determining whether radio frequency retuning (RFR) gaps are available to the WTRU during a multi-CC discontinuous reception (DRX) cycle; scheduling the RFR gap to precede the next activation period in case the CCs in the at least one CC subgroup are inactive for the first subframe after the activation period minus the duration of the RFR gap; scheduling the RFR gap to precede the next active period if at least one PDCCH was successfully decoded by the WTRU during the active period; and In case a different set of CCs can be activated after the activation period, the RFR gap is scheduled to follow the activation period. 15. The method of claim 14, wherein at least one secondary component carrier (SCC) is activated after the RFR gap if the WTRU successfully decodes a PDCCH applicable to the at least one secondary component carrier (SCC). 16. The method of claim 14, wherein the duration of the multi-CC DRX cycle is equal to the duration of the DRX cycle used by the WTRU. 17. The method of claim 14, wherein the duration of the multi-CC DRX cycle is a configurable DRX cycle length. 18. The method of claim 14, wherein the duration of the active period is any one of: DRX on duration, duration of main DRX active time, or duration of the multi-CC DRX cycle. 19. The method of claim 14, wherein the duration of the RFR gap is any one of: a fixed value, configurable by the network, or derived from the capabilities of the WTRU. 20. The method of claim 14, wherein the channel assignment comprises at least one of a DL assignment or an uplink grant.

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